Because for the most part its not a concept of morality to them. So shaming doesn't really do anything, actual consequences like loss of jobs and dissociation from family members, those things may hinder this behavior, but conscience level reasoning is not something that will typically effect this way of thinking. If people view it as an "opinion," they are not going to associate morality towards it. So being racist is a more of a base level of thinking, like "I need to eat" or "I need to exercise."
